1. Field of the Invention
The present invention relates to structures for supporting splitters (also called “riving knives”) of cutting devices, such as table saws. The splitters are positioned on the rear side of a cutting blade with respect to a cutting direction. In this specification, the term “cutting direction” is used to mean a moving direction of a workpiece during a cutting operation.
2. Description of the Related Art
Referring to FIG. 10, a known table saw 50 has a table 51 for placing a workpiece W thereon. A circular cutting blade 52 is rotatably driven by a motor 53 and is positioned such that an upper part of the cutting blade 52 protrudes upward from an upper surface of the table 51. The workpiece W can be cut by the rotating cutting blade 52 as the workpiece W is moved along the upper surface of the table 51 in a cutting direction indicated by an outline arrow in FIG. 10.
If the rotating cutting blade 52 contacts the workpiece W at its kerf that has been produced immediately after being cut by the cutting blade 52, a phenomenon called “kickback phenomenon” may be caused to force the workpiece W upward. In order to prevent this kickback phenomenon, a splitter 55 is positioned on the front side of the cutting blade 52 with respect to the cutting direction (right side as viewed in FIG. 10). The splitter 55 enters the kerf to maintain the width of the kerf to be slightly greater than the thickness of the cutting blade 52, so that the cutting blade 52 can be prevented from contacting the workpiece W at the kerf. Therefore, in general, the splitter 55 has a thin plate-like configuration with a thickness slightly smaller than the thickness of the cutting edge of the cutting blade 52 and is positioned to extend within a same plane as the cutting blade 52.
The cutting blade 52 and the motor 53 for driving the cutting blade 52 are supported on a lift 54 that is vertically movable relative to the table 51. A splitter base 56 is mounted to the lift 54 and supports the splitter 55 such that the splitter 55 extends upward from the splitter base 56. More specifically, the splitter 55 is secured to the splitter base 56 by means of two bolts 56a. 
A cover frame 60 is mounted to the upper end of the splitter 55, which extends upward from the table 51. The cover frame 60 has a configuration elongated in the cutting direction (right and left directions as viewed in FIG. 10). Two covers 61 are vertically pivotally mounted to the front portion of the cover frame 60 with respect to the cutting direction (left portion as viewed in FIG. 10) and are positioned on opposite lateral sides of the cutting blade 52. Two kickback preventing claws 62 are vertically pivotally mounted to the rear portion of the cover frame 60 with respect to the cutting direction (right portion as viewed in FIG. 10) and are positioned on opposite lateral sides of the cutting blade 52. The covers 61 serve to prevent cutting chips, which may be produced during the cutting operation, from scattering to the surrounding environment. The kickback preventing claws 52 can contact the upper surface of a part of the workpiece W immediately after being cut by the cutting blade 52 for further reliably preventing the kickback phenomenon.
While the splitter 55 can perform the kickback preventing function during the cutting operation of the workpiece W for cutting the workpiece W into separate parts, the splitter 55 cannot perform the kickback preventing function or is unnecessary during a cutting operation for forming a flute or a groove with a predetermined width into a workpiece, because a fluting or grooving cutter has a thickness greater than a thickness of a normal cutting blade used for cutting a workpiece into separate parts. Therefore, in general, the splitter 55 is removed in the event that a fluting or grooving operation is performed.
However, because the splitter 55 is mounted to the splitter base 56 that is disposed below the table 51, it is necessary to loosen the bolts 56a positioned below the table 51 in order to remove the splitter 55. Therefore, the mounting and removing operations of the splitter 55 are very troublesome. In addition, there is a possibility that the splitter 55 will be lost after it is removed. In such a case, it is necessary to look for the lost splitter in order to remount the splitter.
For the above reason, Japanese Laid-Open Patent Publication No. 2005-262337 has proposed to enable a splitter to move downwardly relative to the table away from the front position of a cutting blade when the splitter is not needed.
However, with the configuration of the above publication, a part of the splitter still extends upward from the upper surface of the table even if the splitter has moved downward.
Therefore, there has been a need for a support structure for a splitter which enables the splitter to be easily ejected from a position where substantially no part of the splitter extends upward from the upper surface of a table.